Lime mixture



Patented Sept. 20, 1932 nairED sr r-E PATENT oFrric-Ef JULIYUS E. onnnnwoon ANneHAnLEs A. menu, or WASHINGTON, .nrsrnrcr on COLUMBIA, Jessie-noes -ro narroimnmivrnessocinrron, econ-Penman canine,

nrs'rmcr or COBUMBIA N0 Drawing.

This invention relates to plastics and more particularly to improved plaster compositions having quick initial set and hightensile strength.

Hydrated lime and lime putty possess properties which recommendtheir' use forv plastering purposes. The major objection to these substances for-plasteringandsim lar construction work resides in the. fact that they do not possess any quick initial setting properties. When hydrated lim'e is used "for this purpose, it requires from twenty to twenty-four hours before the material hasv acquired such a firm texture faswill sustain a second coat. To overcome this-disadvantage, it has been proposed to addsubstances to the lime not-only to decrease the initial setting time but also to increase .thetensile strength. I a I It is sometimes advantageous torpreparea dry mixture of hydrated lime, orequ-ivalent material, in which is incorporated substances which impart the desired properties, such as quick initial set and a relatively high tensile strength. These mixtures may be made up and shipped to the place of use, since they require only the addition of water to make the plaster. Such dry mixtures, however, have the outstanding disadvantage of gradually deteriorating during storage so that in many cases after an extended storage period the plaster resultingfrom the addition of water, .is lacking in strength andhas a higher setting time than a freshly madedry lime mixture.

An additional object is to provide a treatment for a dry lime mixture having incorporated a strength imparter and an accelerator whereby the addition agents are preserved during an extended storage period.

storage is, prevented,

I MIXTURE Application filed-cafeterias, 1926; Serial No.145,097.

described in Patent N0.-l,65 6,9;84,. a plastic fmateriaal' having the propertiesiloif quick; initial set and high tensile "strength maybe prepared byifncorporating with V hydrated lime or similar alkaline earth material, known amounts. of a' carbonate, sulphate, alum-inate and sugar. covered-that when an aluminous constituent We have dis strea-ted with an o eaginousisnbs anceithe deleterious effect ordinarily resulting afirem The preferred embodiment. ofthe inven-v tion is in the addition ot a smallamount of; an oleag-i'nous material to the aluminous con sti-tue'nt, .the resulting. product beingsubse quently incorporated with the hydratedlime, carbonate, sulphate and sugar mixture. It is to be understoodthat the oilinay be adds ed. to'th'e entire mixture as such, or to oneof: the. other constituents,fthat isitofsay the im venti'on is not limited to the treatment of the alUIIliIlZLlJGJVlth oil.,. A specific example of'the present .i'nven tion is given hereinafter. This is. merely an illustration and is. not exclusivebut is to. be considered as eXemplifyi-ngthe underlyingprinciple of the invention, which is. considered as residing in the conception oi incorporating. a preservative Witha mixture of..the. general character described tothereby prevent deterioration. I To the aluminous constituent, such as @3117:

vciuln aluminate, weaddy-asmall amount of a saponi-fiable oil, such as linseed oil, cotton seed oil or peanut oil and by suitable thoroughly incorporatethe-two.- The result-1 oil; treated aluminate, isthen mixed with the: hydrated lime and other addition agents as: described in the patent-referred to.

fiable oi l, however, may be used and serves well asa protective agent, but the plaster oletained from such mix does not possessthe V the designated periods of storage.

plasticity of thatin which a saponifiable oil is used.

The following table serves to illustrate the advantages obtained when a plaster mix, having potential properties of quick initial set and high tensile strength, is. treated according to ourmethod. In this tablethe time of set is given in hours and minutes and the tensile strength in pounds per square inch at The tensile strength, as determined by the Gillmore needle test, is taken twenty-four hours after the lime mixture is made up into the plaster."

Per Per Per i I cent of centof cent Pet Pe Per Time 5 3 mi: alumiw'hitr Age of set centof centof cent h hr. lbs. c1um num mg days r. alumisulsubstistone Sugar of mm. pet nate phate tute 5* .5 2 30 .3 Fresh 250 30 i 134 3:10 28 351 5:10 13 5* .5 1 30 .3 2 Fresh 3:00 18 v 134 3:15 28 351 3:00 31 i Sufficient hydrated lime to make 100%.

From this table it will be seen that an untreated mix, that is. one to which no oil has been added, after. storage requires a greater settingtime. The storage period in' addition causes a great loss in the final tensile strength. Thus a mixture which has not. been treated with oil when freshly made has a tensile strength of thirty pounds per square inch. A sample of the same material after a storage period of one hundred and thirtyfour" days shows a decrease in strength. At the expiration of approximately a year, the tensile strength has decreased to thirteen pounds, or less than half of the original 'strength'. Similarly, as the storage period increases the setting time of the plaster product increases. Whereas the plaster made from a freshmixture has an initial set of two hours'a'nd fifty minutes, this material after a years storage period requires a setting time We prefer to use oil up to approximately two per cent or one-tenth of one per cent of the aluminous constituent of the total mix. We have found by experiment that this is a very satisfactory percentage, but it is to be understood that in practice the' amount may be varied somewhat, depending upon theparticular mixture to which it is added. The beneficial result accruing from the oil treatment is not dependent upon the particular quantity of oil added.

It is to be understood that while we have described an oil treatment of an aluminous constituent of a lime, aluminate, carbonate, sulphate mixture, the lnvention is not limitedto thetreatmentof this particular substance or the illustrative mixture. W'e conceive our-invention as residing broadly in the production of a dry lime mix com'pris- 7 drated lime, a'carbonate, a sulphate, sugar, MW

and oil treated calcium aluminate.

In testimony tures.

JULIUS E. UNDERWOOD. CHARLES A. CABELL.

whereof we afiix our signa cent of oil, after a storage period of one hundred and thirty-four days has an initial setting time of three hours and fifteen minutes'and a tensile strength of twenty-eight pounds. After three hundred and fifty-one days storage the plaster made from the preserved dry mixture possesses a tensile strength of over thirty pounds. This characteristic efiect of the oil'in serving to main-.,

tain a high. tensile strength obtains at all periods of storage. In addition the described treatment serves to protect the quick setting properties, for, as shown in the tables, after approximately one years storagesthe initial setting time is as low as that of a freshly made batch. 

